If it's mostly TLV-LHR you do, and considering the amount of travel, I imagine you're not looking to connect, then yes, BA is your only alternative unless you're looking to go down the route of EasyJet.
BA have a solid product, and while there might have been a devaluation of Avios a few years back, it's not different to any other airline in that respect.
Like you mentioned, your Avios are handy on other OW airlines (which will help you on your HKG trips) while Matmid points are useless for anything other than LY, plus they expire...

BA Gold will also get you First wing check in at LHR which is fantastic, plus a far better lounge experiance (at LHR, not in TLV obviously).
Are you likely to make it to GGL? Do you only book Economy? And if you switch to BA do you start from scratch, to make it through the Tiers, or are you really still BA Gold as your profile suggests, in which case, you obviously hadn't ditched BA entirely and still do a fair bit of travel with them.