Looks like you are getting some form both sides of the issue here. GOOD!
I will add my 2 cents (since I own the Triumph and the wife has the OV). I prefer the Triumph. I never had any of the issues that most people have reported, although very rarely I have trouble with the back key not working right (which is a hardware issue). The OV is very solid and a good phone. The Triumph does feel a little bit less hardy in comparison, but it is far from flimsy in my opinion. My wife has more issues with her OV than I do with my Triumph (partially because I know a lot more than she does, and she doesn't want to take the time to learn it all). The OV has a slower processor, a smaller screen, and less internal memory. If those are important to you more than other issues, you should remember that.
MOST of the issues people have had with the Triumph when it was released are not being seen as much (looks like they have better QC now). Many more of the issues are solved by putting one of the excellent custom ROMs on the phone, and if you feel comfortable with that I would recommend it. The OV has many similar ROMs (like CM7), but does not have MIUI if you would be interested in that. I am not totally current on all the OV ROMs (my wife is just rooted stock), but it seems like there are some really good ones being actively maintained. I think both are going to have ICS before too long from the looks of things.
Both phones would be a good choice. Especially since Virgin Mobile has a good replacement policy (as do places like Best Buy) on the chance that you would get a phone that doesn't work quite right.
OK, that was more like 25cents, but hopefully it helped. The people responding all had points you should consider so weigh it carefully. And if you buy one and feel it is the wrong choice I believe you can return it for a full refund for 30 days (that might just be Best Buy, I am not totally positive). Both phones have an active community here at Android Forums, so feel free to stop by both and ask some questions!
p.s. I would probably recommend the OV if you don't think you will ever want to root your phone or put custom ROMs on it. If you feel like you would want to do that I would recommend the Triumph as the custom ROMs fix
almost every issue people have had with the phones software. You can PM me if you want any more of my excellent input!

Good luck deciding!