Which ethernet cable to use to connect two houses?

I need to connect two houses with two Ethernet cables (each house has its own router). One cable will be used for router-to-router connection and the other cable will be for used for IPTV connection (between router in the first house and the STB in the second house).

A single cable will need to be something like 50-60 meters according to my calculations. A friend of mine told me to get shielded Ethernet cable since there will be signal drop on that distance and I'm not sure which cable to actually get: Cat5e or Cat6 (shielded or not-shielded)?

You probably built your connection by now but here's an answer anyway :)

Before anything else, when talking about any kind of distance, always choose shielded cables. The shield reduces interference. On short distance, interference can be considered negligible for most home-users; but on any kind of distance, it can be destructive. The rest of my answer is purely based on shielded cables!

The specs limit of ethernet cables are 75m for Cat5e and 100m for Cat6. The cables also have a significant difference in bandwidth capacity, Cat5e is made to reach up to 1gbps whereas Cat6 is made to reach 10gbps. These are theoretical limits, they will vary based on interference, length of the cable, tech used on both sides...

I personally had to do sth similar. My router is in the basement of my house and I wanted to place an access point outside; half way through my garden to have wifi across my terrace & garden. I pulled a 47m Cat5e shielded cable (went up my house, crossed to my fence and along my fence till the installation point). I regret using Cat5e; I get a significant increase in ping (+20%) and a significant packet loss (~7%) while my bandwidth saw a small drop (~10%) but was pretty low to begin with (~20mbps). I now got an internet upgrade to 100mbps (~70mbps real speed) and see a significant loss outside where I get ~55mbps. It's a very decent speed and all but it's a shame knowing that cat6 would have probably given me better result and I didn't install it simply cos the store was out the Sunday I built this..

So if you're worried on price and don't need great speed, for a distance of 50-60m, you can use a Cat5e.

However; in order for your system to be future proof and to get the best possible connection, Cat6 is your best bet!