Hi there,
Someone please help me out which arduino board to go for. I'm really struggling.
In my project I have:
5 FSRs (1 analog pin each)
1 LED uses PWM pin
3 Servos (5V) uses PWM pins
One wire DS18B20 digital temperature sensor
1 ADXL345 3-axis accelerometer sensor(5V)
The sensors are required not just to measure but to set thresholds for when the system should shut off
I'm really struggling
Do you think it would help us to see your proposed schematic and your current sketch?
I don't have any sketch 
Servos don't need to use PWM pins - they can use any pin - see the Servo library documentation.
You don't say what interface the accelerometer needs.
If an Uno does not have enough I/O pins then use a Mega.
Do NOT power the servos from the Arduino 5v pin - give them their own power supply with a common GND with the Arduino.
...R
I don't have any sketch
We can see why you are having trouble.
Please review this link:
http://forum.arduino.cc/index.php?topic=261445.msg1845408#msg1845408
Do you have any experience in writing sketches?
Do you have any electronics experience?
If you don't know, get a mega.