My advice would be to suggest you 'interview' your sister to establish her reasons, (perceived, practical or otherwise), as to why she feels she wants to buy / own / use an ebike.
By drilling in to her main and secondary reasons for contemplating getting such a machine, you, (and her), would be able to reduce a wide selection of potential genres, styles and makes down to a few particular ebike types that would, presumably, match her expectations.
The fact she has an open budget adds more importance to any potential purchase because, really, with such a budget, there should be no excuse for settling for anything other than a perfectly suited ebike that would meet your sisters needs exactly.
Don't listen to friends or forum members here suggesting potential deals or potential bikes they might consider ... and don't dare buy some, possibly cool, possibly fab looking machine simply because it has had 'x' amount of cash knocked off it ... suggesting it is a bargain.
Put another way. If I was on the look out for a dinky little hatchback or estate car, (having established that was exactly what I needed), would I, instead, buy a big old Lexus LS400 limousine ... just because it was an apparent bargain?
Would I buy expensive patent shoes 'offered at half price' ... if they were two sizes too small?
Point is ... if you have a great budget, for goodness sake, spend it on a machine that is likely or guaranteed to serve the remit that, by interviewing your sister, you can tease out of her.
Don't listen to the commercial contingent on here either.
I'm sure some of them are sincere in offering you their two penneth but ... with an open budget and an admission that you are 'out of the ebike scene, you are deliciously ripe for garnering any old B.S that someone can peddle you.
Find out what your sister specifically wants and needs with regards to
practical, technical and personal requirements.
I expect a particular genre of ebike will manifest in both your minds as you discuss options.
... and if 'hill climbing' is actually an issue, (or requirement), make that the number one focus ... and, (if that were so), simplify the thread request, (or start another one), by asking forum members here to relate their own experience regarding the hill climbing attributes or characteristics of their own machines.
If the weight of a machine mattered, consider investigating that aspect.
Same with battery range, etc etc,
Asking questions like "What brands are doiing well at the moment?" ... is a bizarre thing to say, (taking NO account of characteristics or features your sister might want with regards to her anticipated ebike needs), ... but it does sound like a great way of throwing money away!
