Everyone's opinions of 'best' will vary, but what will it be used for? Live, practice, recording? How loud does it need to be? New or used?
If you want a valve amp, you'll be hard pushed to get much that's not used or over 5W for that price.
But I've heard very good things about this 15W Harley Benton https://www.thomann.de/gb/harley_benton_tube15_celestion.htm
. Also sold under the Monoprice and Stage-Right labels, it's basically a repackaged version of the now discontinued Laney Cub 12 (and apparently made in the same factory). Iit should come with decent JJ valves and a Celestion Seventy 80 speaker.
It's going to get reasonably loud before it starts breaking up, and it should take pedals nicely.
Otherwise you really have to look at the solid state modelling amps, which do give you a lot more bang for the buck and a lot more volume. So a new Boss Katana 50W, or a nearly new Boss Katana 100W would be my first port of call, though there are several amps in a similar vein by others at similar prices.
And then there are the non-modelling solid state amps, which give you more volume at the expense of flexibility. E.g. a Fender Champion 100W 2x12". This would give you lots of clean volume, but may not respond to pedals in quite the same way as a valve or modelling amp would.
But move to used amps, and the field really opens up. Very few people who haven't worked in a music shop will know what they all sound like, so you'll probably have to rely on YouTube demos.