Slightly wrong section! Afterall it’s about fitness anyway, not too bad xD
I own the TCR2, so I can give you some hints because I went to the same selection as you, and eventually decided to go for the TCR rather than the Defy.
Geometry: the Defy is considered a sportive bike while the TCR is more race oriented, but the geometry of the 2 bikes is extremely similar. If you go to the Giant’s website and have a look at their geimetry side by side, you’ll notice the differences are extremely limited. The TCR by default has a stem which puts you in a very aerodinamic position, while the Defy comes with a more relaxed angle. That’s easily fixed: if you want a more comfortable TCR turn the stem upside down, or ask the lbs to change it for a different (shorter) stem. If you want a more “racey” Defy follow the opposite process.
Frame material: they’re both alloy but they’re made in a different way, and the TCR is sensibly lighter. The only advantage of the Defy is that it has braze ons, useful if you want to fit a rack or stuff like that.
Components: TCR is miles ahead. It’s not that the Sora components on the Defy are bad, but having a 10 speed setup opens up a HUGE amount of customization, and replacements are plentiful. With 9 speed you’re stuck with Sora, with 10 speed you can choose between Tiagra, 105 or Ultegra (let’s not consider Dura Ace, we’re not professionals) and a lot of third party companies produce 10 speed components in larger quantities than the 8 or 9 speeds. In Taiwan Shimano is pretty affordable, but if one day you need to replace something and you want to save a bit of money, Microshift gives you plenty of options in different colors (and it works nice!).
Wheels: if I remember correctly they are the same, I didn’t investigate them a lot because I already had some Shimano wheels and when I bought the bike I let them keep the wheels and I got a 1600nt discount. No idea about the feel of the standard Giant wheels.
Why did I go for the TCR?
By swapping the stem I got the same relaxed position as the Defy, on a much better (and lighter) frame. Moreover now both my bikes (TCR and Fuji Gran Fondo) run on a 10 speed setup, very convenient for replacements and swapping parts. I paid 22.300nt after discount, the Defy would have cost me around 17500nt, for that price difference it was a pretty easy choice for me.
A lot of beginners tend to prefer triple front mech in order to have an easier life uphill. My experience is as follows:
I’m Italian but I lived far from any famous mountains, so in Italy I’ve always used doubles.
Traveled to Australia and rode thousands of kms, that’s as flat as it can get, only used doubles
Moved to Taiwan, bought a flat bar with a double to go to class/work. I approached a mountain and I started to feel the cold embrace of death: moved to a triple. After no longer than 2 months training with the triple I got a new bike that had a double: I began doing hills pretty easily, and eventually I got used to it, now I have 2 bikes with double front gearing.
A double is a nice challenge if you ride uphill for the first time, but if you just keep pushing you’ll notice that after 2 or 3 weeks you’ll start to feel better, and better, and better, and eventually you’ll forget the bigger ring at the back.
The TCR is a better bike, and that’s the reason why it’s 25% more expensive than the Defy. If you can stretch your budget you’ll get a great bike that can be adjusted to have a comfy ride right when you buy it. If it’s over budget, then the Defy is a great bike that people all over the world praise for being a bargain at its price, and in Taiwan it’s a good 25/30% cheaper than anywhere else.
It’s pretty much a Win-Win for you, I’d vote for the TCR but the Defy was the final contender in my choice for a new alloy bike, after ruling out Merida, Khs, Specialized etc etc.
Since you’re pretty tall, make sure to buy it in a place where they can do the fitting properly. Giant stores usually have all the equipment, just make sure with the staff that they can help you with that. If they tell you something like:“Ordering an L? Nooooo we have an M in stock here, it will be fine for you! Get it today!” just change store, at 1.86 you need a L frame (MAYBE M/L could fit as well, but I’m 180cm and M/L is perfect for me, would be surprised if it was comfy for you).