Replace with same size and bolt pattern
All of the major brands have their proponents; you can't really go wrong with any of them. I looked into this idea myself a couple of years ago when a part broke on one of the original equipment lewmars on my '79 Oday 23. Finding a replacement part was a real hassle. However, I didn't want to spend the money to buy two new self-tailing winches, nor did I want to go through the pain of mounting the beasts. I would recommend that you see if the manufacturer of your existing winches makes an exact size (bolt number and spacing) replacement for your units. That way you can just drop the new units over the existing mounting holes. The time and energy you will save by not having to fill old mounting holes with epoxy, drill new mounting holes, cut out the inner hull liner to attach the nuts to the new bolts, etc, will more than compensate you for any marginal difference between the major brands of available winches. BTW, I am one of those who are big fans of the Winchers. They cost about $37 for a pair; if you are willing to pop for new self-tailing winches (about $1000/pair for the proper size for an Oday 23), why not give them a try before you bust the bank?