Eneloop is pretty much the industry standard, with a great reputation.
Standard white ones seem to have a bit longer lifetime (in terms of charge cycles), and the black Pro ones trade that off for greater capacity.
No, not to the best of my knowledge - and you did say 1.5V. If you need 1.5V, you're probably looking at a regulated Li ion cell of the type fulee9999 referenced. They're relatively new, but there are several on the market now to choose from, and they may not all be created equal, so do a little research with published 'tests', etc. (including anecdotal info on this site). There are threads about some of them.
Here's my problem. I'm running out of AA's rechargeable and since I seem to have had problems with mice and other things, I wonder if it's the fact that I use 1.2v batteries and thought I'd go for 1.,5v rechargeable. The ones fulee suggested, I can't find in the US.
Used to have these progenix or whatever but can't find the batteries and the charger and also, they are very old.
Unfortunately a few poorly designed devices only works at a higher voltage than nimh batteries can provide, so you may be right in your assumption that it is the slightly lower nominal voltage from nimh batteries that causes the problems.
But since there are relatively few devices that do not work well with nimh batteries, and you say you have problem with several devices, makes me think there is a very good chance you either have some bad batteries and/or charger.
I would start by buying a few eneloop batteries with a good charger, and see if that doesn't solve the problem. They are low self-discharge batteries, and there is a broad consensus that they are the best LSD batteries (low self-discharge) on the market. They have just introduced a new fifth generation cell.
See if you can find some of these, otherwise their fourth generation are almost just as good. I don't think there is much difference between the two generations, so if you can only find the fourth generation, that shouldn't stop you from buying them.
ChibiM has an informative website ( https://eneloop101.com/ ) you should read. There you can read exactly which batteries and product codes you should look for, as well as good chargers.
Although low self-discharge nimh cells like eneloop, can be charged by any nimh charger, I would highly recommend a smart charger with individual charging bays, and stay away from chargers with trickle charge, and chargers that charge batteries in pairs.
It is also a good idea to make sure the eneloops are made in Japan, as they are slightly better than the ones they get produced in China. But if you buy from an authorized eneloop dealer in USA, that should not be a problem. They only sell the ones made in Japan.
In terms of longevity, eneloops last a long time under normal circumstances, both in terms cycles and years. My 2nd generation eneloops from 2010 still works fine.
However, they haven't been exposed to many cycles or high drain devices either, it must be said.
As said, I've only had this mouse since January. But I keep track of my batteries, and therefore I can tell you, that I put some fourth generation eneloops in the mouse 15th january 2022 and they had to be charged again 7th August 2022.
But there is an on/off button on the mouse which I have not used. This means that my mouse has been switched on 24 hours a day all seven months. If I had turned off the mouse when I was not using the computer, the charge would have lasted longer.
I personaly have a Panasonic BQ-CC17 charger.
It is a slow but good smart charger. It takes 7 hours for charging 4 AA batteries.
Amazon sell it with a set of 4 AA eneloops (propably fourth generation). But you can also get a faster charger if you want to.
ChibiM recomends some chargers on his website. He also has a thread here on cpf.
Eneloop overview 2005-2021 In February 2017 I started building a website about eneloop batteries called eneloop101.com to get all the information about eneloop batteries , an eneloop charger list and in 1 spot. There is lots of information including pdf product sheets, pdf eneloop catalogs...