What factors should I take into account before buying an Enigma2 receiver ?

List your specific requirements and we would recommend something, but from your post you may be looking for a twin satellite tuner receiver.

Do you want to record much? Is an internal HDD a must? Or is a USB HDD ok?

Not sure why you've posted 'HiSilicon CPUs must be avoided because they cause problems', as this is totally untrue and you've been mis-informed. Our best selling receivers actually have Hisilicon CPU's.

Have you got satellite or cable
When looking for satellite boxes you will need to buy the appropriate included tuners. S or C
Most models do variations of tuners depending on what you want.
If satellite have you got at least a dual LNB if you want to watch/record 2 channels at the same time.

1 tuner - you can only watch the same channel thats playing on your box, or on the same transponder.

2 tuners - you can watch/record a completely different channel.

Whats your budget.

Do you plan to watch ...

freesat - that will work out of the box once your box is setup.

scrambled channels - a card sharing line would be need to be sourced - but this doesn't show the main sky channels anymore . Although underground providers do exist for full sky now.

IPTV - IPTV provider would need to be sourced - then you just download an iptv plugin/player. IPTV will be usually limited to one device at a time though unless you buy a multi room line.

Card sharing and IPTV sources don't get discussed on this forum though.

As for mobile phone viewing - if on the same wifi there are lots of apps you can just download on your phone to view your STB channels. In android store or apple store just do a search for enigma2.

Hisilicon CPUs are the norm. Don't believe everything you read on the net.

Buy a quad core box if you can afford it, you will certainly notice the speed benefit.

For your first box the octagon SF8008 or zgemma H7s 4k is probably suitable for your needs if you got a dual lnb sateliite.
They only about £110 (ish)