The only reason you'd want to buy a 25 key keyboard should be mobility or lack of space. There are some ppl who claim 25 keys are nice to play bass lines on but if that's your only keyboard you're in risk of having a lack of keys later on when you learn to play better.
Otherwise, I'd say get at least 49 keys or more.
I got 49 keys because of money reasons. Now I do think sometimes I should've gotten myself at least a 61 key keyboard but tbh, 49 is cutting it nicely. You can always transpond and producing gives you the luxury not having to play both hands at the same time. If keyboard ain't your main instrument that's something nice anyway. That way you don't need to play as good as you would if that'd be your only instrument in a live setting. You do have to understand the theory behind key, scales, chords, etc.
25 keys is gonna mess your workflow up too much if you have to transpond and/or stop the whole time to put in notes of higher octaves.
I always have in the back of my mind that if I start playing that good, I'll buy an 88 key weighted board so I'll have two keyboards. Not really in risk of this as saxophone and EWI on the computer is my main instrument. Also , controlling the pads is something that needs to be practiced a lot as well if you want to do it Jeremy Ellis style
.
Tried playing the drums and percussion with the EWI but that seems ridiculuous if you ask me. I usually play drums and percussion on the pad controller.
Also, pads on keyboards usually aren't much good compared to propper pad controllers.
The Korg PadKontrol is about the cheapest propper responsive pad controller out there. You can easily pick those up second hand. The cheaper MPDs are around as well, but a lot of ppl complain about the pads on them. There's youtubes out there to get those pads more responsive with ductape though.
The Maschine from NI is something nice as well. Other than that you could go towards MPCs.
Anyway, these are my 2 cents, better buy enough keys now than to be sorry later on.
