While this is sort of a "shopping" question, it is also a question about if these phones will work on t-mobile's network.
T-Mobile does not (currently) have LTE. So if the device has LTE, you will not use the LTE chip.
Will the devices work on T-Mobile? Yes. Will you get the T-Mobile 4G speeds? Well that depends on what bands (or frequencies) the device supports.
T-Mobile has support for the following bands for their 4G netowork:
- 1700 MHz | UMTS/HSPA/HSPA+
- 1900 MHz | UMTS/HSPA/HSPA+
- 1700 MHz | LTE (this is the band they will use when they roll out LTE)
According to the Spec Sheet on Amazon of the i9300:
- 3G Network | HSDPA 850 / 900 / 1900 / 2100
- AFAIK, internationally, HSPA+ is not considered 4G, so based on this, yes this phone will give you T-Mobile 4G
The i9305 on the other had, according to Amazon, does not appear to have the bands available for T-Mobile:
- 4G Network: LTE 800 / 1800 / 2600
- 3G: HSDPA 850 / 900 / 2100
Now, what I am actually making here is just an assumption, because it supports the bands that T-Mobile supports. I cannot say with 100% certainty that it will operate with their 4G speeds.