Don't let your previous experience of the Altberg Defender having little ankle support put you off looking at Altberg boots. Your experience only confirms what I've stated here on a number of occasions. The Defender is ideal as a cheap way of getting a high quality full leather boot suitable for low level walking but for any higher level walking on more difficult terrain you need to be looking at their purpose built walking boot models which do have better ankle support.
If you want quality boots which will last you more than 1-2 years my advice would be to definitely go for a full leather boot with as little stitching as possible in preference to a leather/fabric combination boot.
I would suggest that you make the effort to have a close look at the Altberg range (you may need travel a fair distance to your nearest Premier dealer). They're not cheap but you will definitely not be disappointed with the build quality of any of them and occasional bargains are available online. As a guide I recently managed to buy a pair of Altberg Malham for £130 and a pair of Altberg Nordkapp for £157 from Gaynor Sports in their 30% Off RRP Easter Offer.
Depending on the type of walking you do most the following models may be suitable options. If the model of a boot made on the standard last doesn't quite fit or suit your particular foot shape, width and volume it's a fairly safe be that a boot made on either the A-Forme or G-Fit last will. All Altberg boots can be resoled if and when the need arises.
2-3 Season BootsAltberg Fremington Men's 1412g RRP £179.99 (standard last with 5 width fittings)
https://www.altberg.co.uk/product/the-fremington-mens-boot-mto/Altberg Malham Men's 1344g RRP £184.99 (A-Forme last with 1 medium width fitting)
https://www.altberg.co.uk/product/the-malham-mens-boot-mto/Altberg Keld Unisex 1428g RRP £189.99 (G-Fit last with 1 wide width high volume fitting)
https://www.altberg.co.uk/product/keld-boot-factory-stock/3 Season BootsAltberg Tethera Men's 1472g RRP £214.99 (standard last with 5 width fittings)
https://www.altberg.co.uk/product/the-tethera-mens-boot-mto/Altberg Nordkapp Unisex 1460g RRP £219.99 (A-Forme last with 1 medium width fitting)
https://www.altberg.co.uk/product/factory-stock-nordkapp/Altberg Kisdon Unisex 1622g RRP £219.99 (G-Fit last with 1 wide width high volume fitting)
https://www.altberg.co.uk/product/kisdon-boot-factory-stock/3-4 Season Boots
Altberg Mallerstang Unisex 1768g RRP £239.99 (standard last with 5 width fittings)
https://www.altberg.co.uk/product/the-mallerstang-boot-mto/Depending on which suits/fits your feet the best my personal preference for an excellent all rounder would be either the Tethera or Nordkapp. For me the Nordkapp shades it due to having the higher rubber rand which offers better protection to the leather at the front of the boot.
It's absolutely crucial that you get properly measured first and try them on before you buy. You can find your nearest stockist here
https://www.altberg.co.uk/stockists/ The ones to look for are the Premier Retailers with the red flags on the map who tend to carry a wider range of stock. Wherever you choose to go make sure you phone before you go so you don't waste time and money travelling to look at something that's not in stock. Once you know which model, size and width fitting you require there are occasional bargains to be had online and eBay is always worth a look.
If the Altberg Fremington suits your feet Greaves Sports currently have them available in limited sizes and width fittings @ £135 with an additional up to 8% cashback available if ordered online via TopCashback.
https://www.greavessports.com/sports-c119/outdoor-c4881/footwear-c4883/altberg-m284