I stretched budget on the PSU and went for seasonic looking for longevity and no hassles, I think that is worth it on a PSU as that is a painful thing to deal with when it goes wrong (and I am going to be tech support here). What would you go for if we pushed budget further?
If pushed the dudget further, I'd go for a fully modular to start. This is so you only use the cables you need, and you can add each cable step by step, so can have a little checklist as you build. Also if you damage a cable it can be replaced(as you'll generally have spare pcie cables etc that come with it etc), where if you damage a cable that's attached to the psu, then it's a case of taping it up if the wires ok inside, or you've wrecked your psu...
then I'd look at what you actually think you'd be doing as your upgrade path. So at the mo it's a B650 mobo and 7600...then 6 months later go for a 7600XT gpu? will that be for a couple of years, or is it to go up to 7800xt, 4070 type performance in a couple of years and keep going from there higher....if the 1st, and happy with 1080p gaming, then the requirements on the psu are are lot lower, and you could go for a lower powered more premium psu maybe, a 650w..if you think this will keep going to higher powered gpu's etc, then I'd lean towards a higher psu along the lines of a 850w, esp if you then look at upgrading cpu alsodown the line...also, if you look at going higher gpu, nvidia then I'd also factor in a atx3.0 psu, which can handle power spikes better than non atx3.0...if you look at corsair and seasonic 750w psu, difference from going non atx3.0 to atx3.0 for same psu is a £10 increase in price.
So rambling a little, asif you think you're going to stay lowered powered for next 3/4years etc, then maybe just stick with what you have or go with a modular like the corsair rm650 for £75...it's not top tier(that's the rmx or shift series), but still uses componenets from a tier manufacturers, so the warranty is 7 years...then in 3/4 years, if you upgrade to more powerful cpu/gpu combo look at upgrading the psu at the same time if it pushes the power boundaries..having a 7 yrs warranty means it'll still have value and you can sell it you help fund the upgrade.
going more powerful and going atx3.0 the rm750e is £110 and rm850e is £125..both 7 yrs warranty...going up to 10yrs warranty, then at mo you have purepower 12m 750 atx3.0 at £119, 850 version £130, or MSI mpg a850g for £140
also the 750 seasonci gx750w, non atx for £105(£110 on reoperder on ocuk or add £10 for atx3.0 version)
But as say, no real deals on psu's at more...only a month or so ago you could have got the 1000w version of the msi for £140, and saw the 850w rm850e for £100
actually having a scan around found the rm850e atx3.0 version for £115, and also the msi mpg a850g atx3.0 pcie5 version for £110(same as ocuk selling for £140 above), which would be my pick at mo if going for abuild where going to put in a more hefty gpu/cpu down the line and don't want to start changing power units, and cover bases of nvidia/amd, without going to mad on prices..
keeping low end gpu etc and keeping for a few years, I'd prob stick with something like the rm650 for £75. I's sacrifice the 100w extra for modular and 7yrs warranty, but just me
edit, put below, but remember msi
£110 elsewhere , not for £140 below
My basket at OcUK:
Total: £222.97 (includes delivery: £7.99)