TL/DR: Best angle grinder? -Preferably one that I can swop battery packs with same brand decent cordless hammer drill since my trusty TE-6 is still not functional.

I have a need for an angle grinder.  No - not to break into caves (I find soaking the padlock in a mix of HCl/HNO3 is more subtle and leaves no traces), but to cut up some diving tanks to make novelty toilet roll holders.  Might as well buy a battery one as it might come in handy if I run out of acid need to use it to remove my ladders from Wigmore Swallet and the krabs have rusted shut.  A drill that uses the same batteries and isn't shonky would be useful.  For drilling shot holes not bolting.  I let Max do the latter - he's taller than me and can tie knots properly.

Duncan

Makita 18v is a good range:

https://www.screwfix.com/p/makita-dga452z-18v-li-ion-lxt-4-cordless-angle-grinder-bare/89836
https://www.screwfix.com/p/makita-dhr202z-2-9kg-18v-li-ion-lxt-cordless-sds-plus-drill-bare/48570

I've been using the brushless 456Z model for a while now and it's very impressive - I've cut several scaff tubes with one 4aH battery. And I can share the batteries with the SDS drill. Very good tools.

I would recommend DeWalt . Fantastic bit of kit. Go for the brushless obv

I second Rob's recommendation of Makita. Their range of 18V tools has got to be the widest in the business and it's all good solid kit. I have used and abused a lot of it. They have also been a generous supporter of caving expeditions over the years.

Having had both brushed motor and brushless grinders I would not now consider buying another brushed motor one. The brushless compares favourably with the power of a mains powered tool, the brushed one is feeble by comparison.