1. There's no such thing as best model and year. It depends on what you are looking.
For your budget you could purchase a Bluebird U13, U14 or a Bluebird Sylphy G10
The U13 and U14 are quit similar, these were made prior to Renault got involved in Nissan. Both cars were offered in either diesel or gasoline.
Diesel engine was offered with CD20 engine, later versions received a CD20 electronic engine. Engine prices range from around 200k-275k. Gasoline U13 were available with SR18DE and SR20DE or SR20DET. I think you you only get the SR18DE version in SL.
U14 was available with the same diesel engine, but petrol versions were available with SR18DE, QG18DE OR QG18DD and SR20VE.
The QG18 models were fitted with Nissan's hyper CVT. The diesel version with manual transmission will easily return around 16km/l with AC on outstation drives. I'm not sure about the gasoline versions but they pull very well.
The highest spec in both U13 and U14 was the SSS.
Both cars had front and rear independent suspension hence they are quite comfortable and handle well around corners. However as I mentioned earlier the suspension is designed to absorb potholes and bumps well hence they tend to wear out quickly on our badly maintained roads. Also the body of these cars are fairly heavy. A pair of KYB shocks will cost around 8K while a used pair of original coil spring with shock absorber will cost around 10k.
The Bluebird Sylphy was based on the N16 Nissan Sunny thus it was offered with smaller engine choices. Starting from 1500cc QG15, 1800cc QG18 and there was also a 2000cc engine. However there wasn't a diesel choice available.
This model received independent suspension only at the front and the car is bit smaller than the U13 and U14.
I would recommend you go with a G10 cuz it's newer hence it would be easier to find an unmolested unit.