I think I've had a 9V leak once, I've had others leak internally to the point that the ends were bulging but the outer case gives them an extra line of defense and the smaller internal cells may hold less liquid.
I've been using Eneloops in almost everything for years. I also have some Fujitsu that are supposedly made by the same company, and some of the Japanese Amazon Basics NiMH cells which are also quite good. Some are Chinese so check closely before buying.
Second this ***WARNING*** for LEAKING 9v alkaline batteries.
Recently pulled my (~5 year old like new) 87V out to test a circuit and it wouldn't power on. Pulled the battery cover and to my dismay - Found a Duracell Quantum 9v with heavy corrosion coming out the top of the battery.
Tried to carefully remove the 9v snap connector. No issues with positive terminal but the negative terminals were pretty much chemically welded together. The negative post broke away from the battery and the snap connector with no real force applied.
Pulled the back off the meter to find corrosion down the negative lead at the JST PH2.0 style quick disconnect on the board... basically all visible metal on the negative lead was blue.
The connector pin on the board is still in good shape after cleaning. But unfortunately I haven't been able to find a female connector to match the male PH2.0 like connector Fluke used on the board. Also no luck trying to salvage the original connector... it was too far gone.
If something doesn't turn up for a drop in replacement, it looks like I'll be removing the 2 pin male connector from the board and replacing with a normal JST with an easy to find matching female. Pin pitch ~2.0mm. Male connector ~6.0mm x ~3.6mm. ~5.5mm height from top of board (minus pins going through board.).
I have a similar age 116 that was a gift/freebie from Fluke for the 87V purchase. 9v battery in the 116 was still in good shape, but I immediately pulled and replaced with a 9v Lithium.