Your Match History suggests that you're a support main. As a support main, I have to say that claiming to be the best on the team is pointless.
Let's take a look at your last two games:
http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1746967562/49993479?tab=overview
- The score was 18/18 at 34:24
- You went 0/2/4.
- This is roughly 22.2% kill participation. Everyone else was at 50% or higher.
- Your KDA is 2. The lowest of your teammates had 2.25.
- You placed 21 wards. At 34 minutes, this isn't awful. What we don't know is how efficiently they were placed.
Just from what's visible in match details, it looks like you were definitely part of the problem.
http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1746871939/49993479?tab=overview
- The score was 65/55 at 1:06:22
- You went 7/5/35
- This is roughly 64.6% kill participation. You tied for highest with your ADC.
- Your KDA is 8.4. You had the highest on your team. Second highest was Top with 3.36.
- You placed 32 wards.
- For a game that lasted over an hour, this is abysmal. The enemy ADC placed 26 with only a trinket.
- Were you keeping Dragon warded? The enemy took 5 Dragons, and the late game ones didn't occur after a teamfight. That's a common occurrence when one team has no idea the Dragon's being taken.
- You spammed Elixirs of Iron when you reached full build. You already had Mercury Treads.
- Mercury Treads: 35% Tenacity
- Elixir of Iron: 25% Tenacity
- Mercury Treads & Elixir of Iron: 43.75% Tenacity
- Elixir of Ruin: 250HP, 15% bonus damage to towers for you and minions, movement speed boost for minions. In my opinion, this should've been your elixir of choice to finish the game.
At a glance, it seems like you were the powerhouse of the team because of your kill stats. We just don't know for sure, though. Were you using your actives at the right times? Were you blowing all your skills and then retreating, or did you effectively peel for your carries? You were the primary tank. Typically you're the one who wants to take the brunt of the deaths. If you can die to let a carry limp away, dive and delay the enemy. Your team had four Barons to the enemy's zero. With that sort of advantage, you should've been able to end. If your teammates were twiddling their thumbs, it falls to you to get them moving. Don't stand there idly and blame them for being bad. Do something about it.
If you feel like your teammates are always the reason you lose, you're most likely wrong. Is it possible they're bad? Yes. Is it possible you're good? Yes. It's still very possible and likely that you're making mistakes that you don't realize. "You don't know what you don't know." It's also very possible that the other team is objectively better.