Can anyone recommend a good power bank for an android phone?

[KatyMac]

It's a blackberry if it matters

DD bought one for about £20 and it seems fine - but I just wanted to check

TIA

Used to have an anker one for about £20 from amazon. It was amazing till I lost it

Thanks I'll have a look

I bought a £10 RAVPower powerbank from Amazon.

I liked it enough to buy a 2nd one to go with my daughter's first phone.