some help with speaker placement/purchase

I'm hoping to buy some new speakers. I'm most likely considering stand speakers or possibly compact floor standing speakers ($5-$15k). Without getting into the weeds, I have two possible rooms for listening, and the most likely room has limited/compromised space for speakers: in front of a big bank of windows. I can set them up about 2.5' off the windows/wall but not more than that. 

I've had speakers that need room to breathe (e.g., Magnepan) and I know my room isn't ideal. If I use that room, I'll have to consider some "room treatment" (curtains!) and maybe pull them out, away from the wall/windows, for serious listening. Or I may just use the other room, which would give me more space to work with and no window problems but would be less ideal for a few reasons; or I may decided that, given my space, it's not worth buying high-end speakers at all.

So here's my question. Other than a home audition, is there a good way to know whether a speaker is forgiving about placement? Are certain speaker brands known to be more forgiving about the space behind them? Would one size (stand or floor) be inherently better? And specifically: would a ported speaker in general be worse/better or does it just depend entirely on the speaker/room? (I'm intentionally not naming the speakers I plan to audition--I don't want to go down the speaker-recommendation rabbit hole at the moment--but I can name names if it helps; I'm trying to ask a general question here.)

I would appreciate any thought about purchasing speakers that might end up in front of a bank of windows. As always, thank you to this great forum for all the advice!