Bigger isn’t always better it depends on what you wnat to do.
How much of an issue is money? I have a pair of these which I keep in the car and for what they they’re excellent, small, cheap, surprisingly bright and clear optics for 8×21
Pentax bins
Not much more gets you these, bigger apertures which would give a wilder field of view and brighter image. Not used them but Olympus is quality stuff on the camera front so I can’t see the bins being kak
Olymous bins
Ran up to £100 on the wex web site but couldn’t find anything else to recommend but dd find these at £110. 12*50 is probably a bit heavy on the magnification v aperture front, but of magnification is what you’re after, Pentax is optically good kit IME
Pentax bins again
BTW, I used the wex site deliberately, may be not the cheapest but I’ve always had a positive experience dealing with them