Actually, I am playing both a chain-lock and a blade-lock.You're making a lot of subjective claims here without backing most of them up, and you sound more than a little hyperbolic/optimizey. Why exactly are chain-locks "piss-weak"? Does "piss-weak" mean they're broken-underpowered, or do you mean that tome-locks are broken-overpowered by comparison?
Just a heads-up before you respond: If you think something is actually broken, please say so, and say why. If you just think you'd never choose to play one because you find them underpowered, then, with respect, please don't let the door hit you on the way out.
But in purely mechanical terms, the pact-lock has the biggest bang for the buck. Familiars just aren't very powerful. Handy, but then again their primary use would be in scouting which merely takes away from the PC's who would prefer to do it themselves. The pact familiars are a bit better with their powers but even then, putting them in combat is a sure way to get them killed. Not a major hassle but it still means in terms of power, they're just not that great.
The melee-lock is ok in terms of power but, as I said, being in melee means sacrificing your most powerful attack, that being Eldritch Blast with Agonizing Blast. It also means taking two invocations across 12 levels in order to give it enough power to be decent.
I was merely disputing that the tome pact was bad. Just because the power of when and where and what rituals you come across is in the hands of the DM, does not mean it's a bad pact. Even without getting extra rituals, the fact that you get three extra cantrips from ANY class and can use one of your first invocations to get two 1st-level rituals from ANY class, makes it far and away the best optimal choice from a purely mechanical advantage perspective. That this advantage can be increased is merely icing on the cake.