Should i use 2.4 Ghz or 5 Ghz frequency band ?

Network Gear Situation:

With respect to frequency bands (or wireless carrier), Router are classified as:

1. Single band - Will support only 2.4 Ghz band (entry level)
2. Legacy Dual band - Will support both 2.4 Ghz and 5 Ghz but only one at a time
3. Dual band - Simultaneously operate both the frequency bands
4. Tri-band - Will support TWO 5 Ghz bands and ONE 2.4 Ghz band

Each frequency band means a virtual logical router in itself with independent SSID (Wireless network name)

A client will support either 2.4 ghz or 5 Ghz at a time. Never both simultaneously even though it cant support booth the frequency bands. And a lot of legacy Wifi clients or simple devices uses 2.4 Ghz only with only the latest ones being able to support the 5Ghz band additionally.

Tradeoffs:

1. 2.4 Ghz has more range (will reach father from router/AP) but will suffer more from interference with neighbor's network. 
2. 2.4 Ghz has more client support (and therefore more ubiquitous)
3. 5Ghz has less range and faces less interference from neighbor's network
4. 5Ghz has fewer client support (only modern devices). 
5. 5Ghz suffers more attenuation from walls and household objects and performance falls drastically outside the room where AP/router is placed. 
6. 5Ghz has more channels and more bandwidth compared to 2.4 Ghz

Here's a reference graphic comparison:

Which will give better throughput ?

Hard to verdict with 100% confidence. It depends on what factor dominates a deployment scene. Generally if we get a good signal strength, it will be the 5 Ghz band (less interface, more bandwidth). But this changes from home to home. If signal crosses more walls, 5 Ghz range dramatically falls and makes it unusable and worse than 2.4 Ghz.

It should be clear why I hate Wifi. To many ifs and buts ...

- Suman Kumar Luthra @ APRC-P3 Telecom Sub-Committee