Top brand cordless tools with Li-ion batteries are now very good. The fundamental issue is that you really need to carefully decide which brand to sign up to. The batteries are probably the most significant part of the investment, and once you decide on your brand you're more or less committed to that for all your tools.
Personally I'm with Makita, but Bosch, De Walt, and Milwaukee are all reliable good quality stuff with pretty big range of tools. I still have some 3Ah batteries which are nearly 10yrs old, one is getting a bit tired but still usable. The problem I've seen with other folk who have used for example Ryobi is that not only are the tools much less robust but the batteries don't last, a couple of years and they are shot.
If you only want one specific tool then it's a different matter. If you are likely to want more cordless tools then I'd always recommend paying the extra for the big name stuff, see what the tradespeople use for the evidence. There are some good online retailers of the big brands at fair prices, very often 10 or 20% less than the well known outlets. You can save big money by getting bare tools (no case, no battery, no charger etc) once you have the basic kit.
Some retailers I've had good deals from are
https://www.lawson-his.co.uk/ ,
https://www.ffx.co.uk/ ,
https://www.howetools.co.uk/No commercial connection, just good service experience.