I am a big fan of the Aquapure Traveller at £40ish
High performance water purification bottle for travel The Aquapure Traveller™ (APT) is a high performance personal water purification bottle designed to produce safe drinking water from unsafe sources of supply worldwide. This water purifier will provide against waterborne disease and...
purehydration.com
estimate of 350litres, which is more than the Grayl, and it is certainly lighter. They do some other products too, like an inline unit for gravity feed. I have had my Traveller in Sweden, the US, Hong Kong, Namibia, and New Zealand. Several of those had pretty clean water, so didn't tax it. I didn't use it in the jungle because the silt load in even clean jungle streams will clog the filter element of any system, even back flushing doesn't help for long. I used the Traveller in the English Lake District and tried it on water from one of the unappetizing looking pools found up on the high tops, worked well and didn't even taste bad.
Not to detract from the Grayl, which would be one of the three products I would recommend. The third being the MSR Guardian.
I had an MSR Miniworks, which was a little smaller and lighter than the Guardian, and I couldn't generally justify carrying it unless I was with a group, so I look at the Guardian as a good choice for two or three people. I actually used the Miniworks as part of a canoe trip of eight. Lots of pumping.
While Lifestraw does have a purifier, most of their smaller bottle size products in the £40 range are filters only and do not remove viruses. Same goes for Sawyer as far as I know. Good filters, but that is not the same as a purifier. I bought a Sawyer Mini back in 2016 and have yet to use it! My Traveller bottle has been so convenient, and light, and takes out everything.
Chris