Lordship Lane, to be frank, only really has the nice (but generally over-priced) high street going for it. The fact our transport links are better already, and will get more so, has already been mentioned - but what hasn't is that many of those pretty-looking terraces off LL have quite poky houses, especially considering the higher prices. You would for instance, probably get larger rooms for your money in a 4-bed house in FH, and are likely to get a larger living room in a 2 bed conversion flat here than off LL. And don't start me on gardens...
Anything you find you do want from Lordship Lane is only a short bus ride away, even from the Perry Vale side of the railway - so why bother? Buy here, and get the best of both worlds (until our own High St gets some TLC and improves).
Forest Hill is much more varied than ED, both socially and in terms of things to do. And fairly friendly - especially for London, which I know can be an issue for Northerners! The green spaces, and views from the hill give you a wide open horizon which really lifts the spirits at the end of a week working in the towering, closed-in urban sprawl. Sure this helps us all keep calmer than elsewhere in The Smoke! If Sydenham Hill Woods or One Tree Hill (both within walking distance) aren't green enough for you, it is as quick to get into the countryside as it is to get to the centre of town, so you can do frenetic townie stuff or get down with nature with equal ease. Or stay put and have a laugh at The Hob!