trimming worktops needs somethign with some grunt – 1/2″ and big motor (and use a fresh cutter each time). Most people will leave worktops to someone with the right jigs and experience, tbh – it’s so easy to get wrong and it spoils the look of the whole kitchen if you don’t get it 100% right.
for the other stuff a smaller 1/4″ one would be fine.
Like all power tools you can do the job with a cheap one but you end up fighting the tool to get a decent finish out of it. Themore you pay the more bells and whistles you get and the easier it is to use it.
I’ve got a Trend seems to be a good compromise for price/performance.