I really appreciate the responses and helping me to understand some of the finer points of this game. Typically I play the heck out a game I enjoy, but rarely do I get so into it that I focus on min/max stuff. I never want the enjoyment of the game to be overshadowed by the stats or analytics of a game. Some people really enjoy figure this stuff out and while I do like to be efficient when I play, if the way I have more fun takes longer to level then so be it. I just don't want it to take a lot longer if you know what I mean. haha
I have over 560 promotions altogether but I dont have a solid answer based on testing. Normally I try to focus on what I consider less boring and less grindy (if there is such a thing) and I usually lean towards the idea of more XP per game rather than more games per hour.
I and my friends tend to play on regular maps when there are melee characters in the party and Fereldan Castle when everyone agrees to go ranged. We normally abhor low XP kits. Getting 35k XP on the regular maps and 60k on FC is quite satisfying.
We did a full trash XP party the other day (Reaver, Alchemist, Assassin and such) focusing on fast paced games and trying to see if we could change our mentality, but after a few games of 14-17k XP each, we gave up.
Understanding which classes generate more XP is a great point, and while I've always known support tends to get more if played correctly, I was not really aware of how some of those other classes could do so poorly. Makes me think the Hunter is at an even more disadvantage than I thought due to not having any way to detonate a combo, and only KP to set one up. 
It's possible to get 90k+ assuming you use 2x AW, 1x keeper, 1x ele, and trigger hundreds of dispel combos throughout the run. this can also be done with a virtuoso by spamming Mark of the Riff (+ weaken upgrade for sleep) and autoattacking while on static cage while another guy takes the job of dispelling via MB/dispel as many times as possible to trigger additional combos
There are also various ways of doing these things on your own. E.g. Playing the AW with a SF, PotA, MB, CL build and repeatedly chaining PotA -> CL (full mana from restorative veil) -> SF (sleep) -> MB (detonate).
Honestly, I don't really have a clear answer, but my guess is you don't have to worry about these things. Maybe what you can try is to replace fadestep/fadecloak with an eldritch detonator provided you have enough survivability, and just occasionally trigger combos without focusing too much on the small details
Basically putting more thought into team play and the combination of characters used can generate a good xp boost, either to maximize xp or offset a more casual gameplay. I've paid some attention to this, but at times with pugs it can be hard to setup these high xp teams. I have also been trying new builds that use more combo skills, which can be fun and now I know may even lead to more xp. Thanks
well as always there are multiple objectives people chase.
for pure xp and level 1 to 20 promote in 5 runs will be perilous FC with faction boss and killing the boss last as suggested above typically produce 50-90k dependent on who you bring and how you run it
for many who are still looking at combination runs, completed runs, and gold for the challenges and banners, as well as short attention span xp gains the old maps provide a fast speed run the old fashion way.
True that each person can have different goals or methods of achieving those goals. The big takeaway I see from your post and some of the other posts is understanding the xp range for a completed game. Since xp is shared (at least most of it as I thought we get some personal bonus xp based on our medals but have no confirmation) then I have never really paid much attention to the scores at the end of the match as it feels more anti-team to focus on it. Some players always feel they are a better gamer/player because they finished number 1, but most games all that means is you were the most aggressive and usually you were able to be aggressive because others in the team supported you. In DA support xp is so high and your able to earn it in silly ways like standing in fire or lightning, etc. so being the most aggressive is not as rewarded as in some games, and I can see the overall team benefit to maximizing everyone's xp generation. That makes me feel the best player is someone who can help all players in a game generate a high score, and not necessarily the player who ends up number 1.
Question: In me3 the player who setup a combo got the biggest xp boost if I recall correctly, so does damp work that way too?
There are lots of ways to maximize XP, but they require a team of players coordinated with each other and willing to play specific roles or builds. Otherwise you're not maximizing xp and just in a meh pug.
Good point, and while I do not have a regular group of people I play with I have noticed that it can be hard for even good groups to coordinate a play style that maximizes xp generation. Sometimes that is because some people who play are laid back and don't care what others run, and sometimes it is because some players feel that have to be number 1 at the expense of the other players. I used to have regular buddies I played damp with, but they were not into it as much as me and have moved on, but we always used to talk about creating specific builds to play off each classes combos/strengths. We also talked about doing silly things like playing 4 of the same class with each person having to have a different build and no skill used more than twice. Never really got around to doing that, but I think it would be cool to find that regular team who can have fun, and work to gain above average xp.
Thanks to all who posted. I feel I have a better understanding of the xp process, and if a Perilous match can gain around 50-90k xp that gives me an idea of when my group is being efficient or not. (Still some questions though) I can say it is disappointing that some classes are sort of handicapped in this area, but it sounds like only a few and that others just need to be built to better utilize skills that generate more xp. I really like the idea some of you mentioned about using melee classes more on the old maps and ranged on the FC so it won't feel awkward if grouping with people trying to max spawns and xp.
Question: Does non-support xp get generated based on damage dealt like in me3 or do you only get xp for the kill or an assist? (Meaning say an archer with 3k hp and you do 2k dmg but someone else gets kill. Will the kill shot outscore in xp the player who actually did more dmg?) Oh and before you say something like "it pops up on the screen" I have all dmg numbers on and most of time I can't tell who is doing what in way of dmg let alone notice the muted xp numbers that pop up...
It was very clear in me3 how much xp you got for a kill or assist, but not so much in damp to me.