Keep it SIMPLE......
There is no "BEST". Each option has pros and cons, and you will see lots of varying opinions on here and by the bankside depending on everyone's personal experiences and the type of fishing they do. There are a few goolden rules though...
Cheap line is cheap line, it doesn't matter whether it's mono or fluoro or whatever. You spend a lot on fishing tickets, fishing gear, petrol to get to the venue, etc. Choosing a cheap leader line is just pointless.
Get the best, whichever type you choose to go for. Beware, cheap/rubbish fluoro is not that cheap, but it is rubbish, just like cheap mono. Some anti-fluoro views have been formed from experience of rubbish fluoro (that still costs a lot).
Fluorocarbon is more expensive than mono, like for like (i.e. good quality fluoro vs. good quality mono). Fluoro's main benefits are it isn't seen by the fish so easily (despite it being seen by you just as easily) and it sinks more easily / quicker. I have tested the visibility claim quite thoroughly (i.e. not just looking at it through a glass jar, which completely defeats the test). Fish bump into it before being startled. In clear water that could be a valuable benefit. When you don't want the leader to be floating on the surface it helps there too, but you can also get mono to sink too by rubbing Fuller's Earth on it (or equivalent). If you are not fishing in such clear water, the visibility benefit of fluoro is reduced (in my opinion), although even "murky" water is still quite clear at short distances.
I use Riverge fluoro for everything, and I catch a lot of fish. I caught a lot of fish too with mono but years of fishing with boat colleagues has persuaded me to switch. It may have been coincidence that I became better than my mates at catching at the same time I switched to fluoro, or the fluoro helped - we will never know. But the key thing is that I'm happy and I get on with my fishing.
Something I did learn when switching to fluoro is that
it hates wind knots more than mono. If you tend to get a lot of wind knots I would suggest sticking with a good mono until you have sorted your casting out to the point that wind knots are rare.
Fluoro is more fussy about knots - quality of tying them and the types being used. It's worth wasting a couple of metres of the stuff to test this out for yourself with the knots you use, in the way that you tie them (wet of course) - and give them some shock treatment. On doing this I have settled on knots that I have utmost confidence in, and I can't remember the last knot failure. That confidence is worth a hell of a lot more than 2 metres of wasted fluoro!
I just tie a thick bit of mono (15 - 18lb) to the end of my fly line (needle knot) and then 4-turn water knot a straight piece of leader to that. Simple. Some of my mates use loops, some braided bits, some get the glue out, and so on. I've just gone with the simplest way to get the leader turned over and fishing, with only one easy knot to tie if I change the leader. I don't believe I have any presentation delicacy issues, so this works for me. Others will have a system that works for them, which is great. When you get a few views in about this, try them out and see what is simplest for you, so you can forget about it and focus on the fishing.
Just imagine this scenario - you are fishing into dusk, only a few moments left to fish. The lake is bubbling with activity ... a big fish rises regularly near you. A quick cast to it .. oh ****** the leader's tangled in a great big mess. You need to put a fresh leader on quickly in the gloom. The fish is still there ... it's a monster and it's feeding avidly. Choose a system that will get you catching that fish as quickly as possible.