If they did the same things I would better understand your dilemma.
But isn't the first a bluray player, the second a changer and the third a modest CD only player?
What system do you have, and what do you need to be able to play? And if not in the UK, what are their prices in your location. For example, in the UK, the Oppo costs about twice as much as the Rega, so not really comparable at all.
It's a bit like asking do I buy a Mini, a Golf estate or a Merc SLK!
If you go for OPPO 95EU beware that the cooling fan might be noisy according to some users' feedback. I am using OPPO 83SE NU edition which IMHO is good enough to suit my taste. There is no issue on fan noise in this universal player.
I have a Rega P3-24 turntable...Energy C-5 floorstanding speakers...old Marantz 1060B integrated amp.....and Marantz cd 5003 cd player. I will be getting a McIntosh MA 6300 integrated amp next month. I'm looking at possibly purchasing a used MCD 7008 player that has been bought up to specs from a McIntosh dealer. I thought about age and it seems everything is replaceble on the Mac player but the transport. It's had good reviews and great sound. I guess what I was looking for is to see if anyone had experience listening to the three players.
I have no experience with the others except OPPO 95 that I had a chance for its audition when launched. The picture quality is excellent if you use it as a BD or DVD player (but not much different from my 83SE). As to the 2 channel sound its characterisitics is also very GOOD but is not the same as my OPPO 83SE NU. OPPO 95 has better mid range reproduction and having "tube" feeling. Its soundstaging is a little bid better than 83SE. If you like McIntoch I believe you should like the sound from OPPO 95 for music playback.
Having said all these however audition is the most important as music perception is different from person to person due to different freq. response of individuals' ears.
CA 751 is also worth considering the picture of which is very similar to that of OPPO 95 (but the price is £100 cheaper ).