Blazes can beat mongoose when they are alone. The problem is blazes are useless against mongoose with pillars/shields. ACU range upgrade + OC is a better counter to mongeese on small maps.
Obsidians are really good unless kited or OCd. The good news is that they can survive a single storage OC (they require about 10k energy storage to kill, I think).
Aeon TMD are the best if and only if you can build 2 near each other. This guarantees near invulnerability to missiles. A single TMD can be easily defeated with two TMLs or TMD firing in close succession.
Swifties are not so much better against T1 inties that they are a guaranteed air win. The main advantage to Swifties is that they kill Strat bombers almost as well as ASFs, so having a few swifties on-hand means you won't get obliterated by an enemy getting T3 air ahead of you and rushing a strat bomber. 5 Swifties can shoot down an unescorted strat bomber. 10-15 swifties can take down a few ASF and generally hold the line until you can get T3 air yourself. (Don't try to use swifties to hold against T3 air indefinitely... They get obliterated by half their mass cost in ASF.)