Which one is better for combat FDL or Python
It's not as clear as some players here are claiming... Personally I've won most 1v1 vs FdLs in my Python. It's usually only problematic when they are using feedback rails, because the Python heavily relies on SCBs. If you mod your shields for high resistances and are able to get most of your SCBs through, the Python has higher total shield strength than an FdL.
It has a few other advantages apart from that:
1. More firepower. 3l, 2m with a C7 PD are simply superior to 1h, 4m with a C6.
2. It's much more flexible... you can add a cargo rack and a limpet controller to scoop up all the mats, without hurting your overall survivability too much, for example.
3. Getting around is much more comfortable in a Python. It has reasonable jumprange, a huge tank and can fit a fuel scoop without any problems. The FdL is by far the worst of all ships to move around in. Never used an FdL because I just can't stand this crappy combination of bad jumprange, tiny fuel tank and no room to fit a scoop without crippling its combat capabilities. Definetely something to take into consideration.
4. Last but not least: It has a higher mass lock factor, so if anything goes wrong you can low wake almost instantly.