for the same price I can buy a Fender Rumble 25 watts or a Warwick BC 40 watts.
I am a beginner and I would NOT play loud.
I like jazz, funk and slap.
I know Fender is better brand and quality, but the BC 40 has bigger speaker (10’ vs 8’ of the Fender) and a tweeter.
I would like to know please your suggestions and opinions, considering my main need is to have a good and crispy sound for slap.
I would play it with a Marcus Miller V3.
I don’t think this is guaranteed at all. Warwick makes higher end instruments than Fender - not sure about their amps though.
I have owned a Rumble 25 and it’s a great little amp, can strongly recommend it. But for those two for the same price I would go for the Warwick - it’s getting good reviews and the 10" speaker will sound better than the 8" in the Rumble.
I’d consider the other differences as well. For instance, the Fender has only one input channel, but it has overdrive and contour controls. The Warwick has two input channels, one active and one passive, that can also be used to connect two instruments simultaneously, but no overdrive. The Warwick also has automatic compression, the Fender does not. On the other hand, the Warwick weighs 16 kg, the Fender only 9,5. It depends on what’s important to you.
I had a Warwick combo a few years ago, 250w with 15" speaker and another smaller speaker (Sweet 25.2). I think it was my first bass amp. I bought it used and it was a great deal at the time … but I never really liked this amp. it sounded very cold to me. The cab part was fine, but the preamp was not so good IMHO.
That said, for a practice amp, a 40w 10" could be fine ! the speaker size might be the most important here ; 8" is tiny for a bass.